OBJECTIVE Evidence on the association of vitamin D with cardiovascular risk factors in youth is very limited. We examined whether low serum vitamin D levels [25(OH)D] are associated with cardiovascular risk factors in US adolescents aged 12–19 years. METHODS Cross-sectional analysis of 3,577 fasting, nonpregnant adolescents without diagnosed diabetes who participated in the 2001–2004 National Health and Nutrition Examination Survey (NHANES). Risk factors for cardiovascular disease measured using standard methods and defined according to age-modified Adult Treatment Panel-III definitions. RESULTS Mean 25(OH)D in US adolescents was 24.8 ng/mL; lowest in black (15.5 ng/mL), intermediate in Mexican American (21.5 ng/mL), and highest in white (28.0 ng/mL) adolescents (p<0.001, for each pair-wise comparison). Low 25(OH)D levels were strongly associated with overweight status and abdominal obesity (ptrend<0.001, for both). Following adjustment for age, sex, race/ethnicity, body mass index, socioeconomic status, and physical activity, 25(OH)D levels were inversely associated with systolic blood pressure (p=0.02) and plasma glucose concentrations (p=0.01). The adjusted odds ratio (95% CI) for those in the lowest (<15 ng/mL) compared to the highest quartile (>26 ng/mL) of 25(OH)D for hypertension was 2.36 (1.33, 4.19); for fasting hyperglycemia 2.54 (1.01, 6.40); for low HDL-cholesterol 1.54 (0.99, 2.39); for hypertriglyceridemia 1.00 (0.49, 2.04); and for metabolic syndrome 3.88 (1.57, 9.58). CONCLUSIONS Low serum vitamin D in US adolescents is strongly associated with an increased prevalence of hypertension, hyperglycemia, and metabolic syndrome, independent of adiposity. Whether the low concentrations of vitamin D among adolescents predicts future adverse health events remains to be determined.
The DASH diet is likely to reduce coronary heart disease risk. The possible opposing effect on coronary heart disease risk of HDL reduction needs further study.
This relation was unchanged after additional adjustment for PTH level (OR, 0.26; 0.15, 0.44; P trend !0.001) and did not differ by sex (P interaction 0.6) or age (! or R50 years; P interaction 0.2). In contrast, the multivariable-adjusted odds for MetSyn increased with increasing PTH among older men (P trend 0.004), but not younger men (P trend 0.4) or women regardless of age (P trend 0.4 in younger and older women). Conclusions: These data suggest an inverse association of 25(OH)D with MetSyn, independent of potential confounding factors, calcium intake, and PTH, and a positive association of PTH with MetSyn among older men.European Journal of Endocrinology 159 41-48
IMPORTANCE Foods that have similar carbohydrate content can differ in the amount they raise blood glucose. The effects of this property, called the glycemic index, on risk factors for cardiovascular disease and diabetes are not well understood. OBJECTIVE To determine the effect of glycemic index and amount of total dietary carbohydrate on risk factors for cardiovascular disease and diabetes. DESIGN, SETTING, AND PARTICIPANTS Randomized crossover-controlled feeding trial conducted in research units in academic medical centers, in which 163 overweight adults (systolic blood pressure, 120–159 mm Hg) were given 4 complete diets that contained all of their meals, snacks, and calorie-containing beverages, each for 5 weeks, and completed at least 2 study diets. The first participant was enrolled April 1, 2008; the last participant finished December 22, 2010. For any pair of the 4 diets, there were 135 to 150 participants contributing at least 1 primary outcome measure. INTERVENTIONS (1) A high–glycemic index (65% on the glucose scale), high-carbohydrate diet (58% energy); (2) a low–glycemic index (40%), high-carbohydrate diet; (3) a high–glycemic index, low-carbohydrate diet (40% energy); and (4) a low–glycemic index, low-carbohydrate diet. Each diet was based on a healthful DASH-type diet. MAIN OUTCOMES AND MEASURES The 5 primary outcomes were insulin sensitivity, determined from the areas under the curves of glucose and insulin levels during an oral glucose tolerance test; levels of low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides; and systolic blood pressure. RESULTS At high dietary carbohydrate content, the low– compared with high–glycemic index level decreased insulin sensitivity from 8.9 to 7.1 units (−20%, P = .002); increased LDL cholesterol from 139 to 147 mg/dL (6%, P ≤ .001); and did not affect levels of HDL cholesterol, triglycerides, or blood pressure. At low carbohydrate content, the low– compared with high–glycemic index level did not affect the outcomes except for decreasing triglycerides from 91 to 86 mg/dL (−5%, P = .02). In the primary diet contrast, the low–glycemic index, low-carbohydrate diet, compared with the high–glycemic index, high-carbohydrate diet, did not affect insulin sensitivity, systolic blood pressure, LDL cholesterol, or HDL cholesterol but did lower triglycerides from 111 to 86 mg/dL (−23%, P ≤ .001). CONCLUSIONS AND RELEVANCE In this 5-week controlled feeding study, diets with low glycemic index of dietary carbohydrate, compared with high glycemic index of dietary carbohydrate, did not result in improvements in insulin sensitivity, lipid levels, or systolic blood pressure. In the context of an overall DASH-type diet, using glycemic index to select specific foods may not improve cardiovascular risk factors or insulin resistance. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00608049
Supplementation with vitamin C or vitamin E alone reduced lipid peroxidation to a similar extent. Supplementation with a combination of vitamins C and E conferred no benefit beyond that of either vitamin alone.
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